1. Field of the Invention
The present invention relates to an ink jet recording material for recording thereon picture and letter images, and a recording method using the recording material. More particularly, the present invention relates to an ink jet recording material capable of recording thereon ink images having a high clarity by using a coloring pigment-containing ink with no or very little blotting of the ink, and a recording method using the recording material.
2. Description of the Related Art
With the progress of ink jet color printers in producing colored hard copies at a high speed, it has become possible to provide high dignity ink images having high clarity and color density. However, to further enhance the dignity, chroma and appearance of the prints and the quality of the images, the recording material is required to exhibit further improved recording properties. Particularly, in response to the increases in printing speed, resolving power, and chroma of the images, the recording material has been required to exhibit other improved properties, such as an enhanced ink-drying property, an ink absorbing capacity, a dot-size-contrlling property and an ink blotting-preventing property. To respond to the requirements, various types of recording sheets have been developed. For example, Japanese Unexamined Patent Publications No. 55-5183 and No. 56-148,585 disclose an ink jet recording sheet having an ink recording layer formed on a substrate sheet and containing a porous inorganic pigment, to enhance the ink absorption by the ink receiving layer. On one hand, currently, the use of the ink jet printer is expanded, in addition to letter-printing use for making books, to large width poster-printing use for advertisements.
The ink jet printer is very easy to operate and is suitable for printing use in a small amount and thus is distinguished from another printers using printing plates. Therefore, the ink jet printer can produce prints, having necessary images and by a quick operation, in a necessary amount. In the printing for advertisement, a plotter, which can print in a large width, is usually used. The plotter must be able to print ink images for advertisement use with such a high clarity that the printed images can be clearly seen even from far away. Also, the printed images must be able to keep the images in a high-clarity condition over a long period of display. However the conventional ink for the ink jet printing is a dye ink which is oxidized under ultraviolet ray-irradiation or by ozone, and thus the dye ink images are faded and advertisement display is digraded. To solve the above-mentioned disadvantages, it has been attempted by Japanese Unexamined Patent Publications No. 9-157,559 and No. 9-132,740 to replace the dye ink by a coloring pigment ink having a higher light fastness than that of the dye ink. However, it should be noted that there is a difference in the coloring mechanism between the dye ink and the pigment ink, because the coloration by the dye ink is effected by dying the ink receiving layer with a low molecular dye compound, while the coloration by the pigment ink is carried out by spreading or placing pigment particles over and in the ink receiving layer surface, and thus the necessary properties for the dye ink-recording material are different from those for the pigment ink-recording material. Also, the molecular weight of the pigment is significantly larger than that of the dye, and the color fixing mechanism of the pigment to control the blotting of the ink is quite different from the reaction mechanism of the low molecular dye with the ink receiving layer, and thus the conventional ink jet recording material for the dye ink is not appropriate to the pigment ink and cannot record thereon pigment images having a satisfactory color density and a sufficient blot-resistance.
When the ink jet recording material is used as a label having an adhesive layer formed on the backside of the recording material and a release sheet attached to the adhesive layer, the ink images recorded on the label are required to exhibit a high stability over a long time of storage, and thus the ink jet recording material for the label must have a high applicability to the pigment ink printing.
The conventional pigment ink printing system is disadvantageous in that the recorded pigment ink images have an unsatisfactory color density in comparison with that of disperse dye-dyed images, and when the pigment ink is applied in an increased amount to the ink receiving layer, to enhance the color density of the printed ink images, the resultant ink images exhibit a poor color fastness to rubbing and thus when rubbed, the pigment images easily become lighter and the non-printed portions of the recording surface are stained by the pigment. Also, the pigment images have a poor color fastness to water and thus, when wetted with water, the wetted pigment images are easily blotted. The above-mentioned disadvantages are due to the fact that the printed pigment ink is not fully fixed to the recording material. Therefore, the ink jet recording material suitable to the disperse dye ink-printing system cannot solve the above-mentioned problems.
For the disperse dye ink-printing system, there are various attempts to enhance the water resistance of the dye ink images. For example, in Japanese Unexamined Patent Publication No. 9-188,062, a water resistance-enhancing agent is applied to the dye-ink receiving surface before and after the dye ink images are recorded thereon. In Japanese Unexamined Patent Publication No. 55-66,976, the water resistance of the disperse dye images is enhanced by using, as a solvent for the ink, a volatile organic solvent and jetting imagewise the resultant dye ink toward the recording surface. However, in the system in which the water-resistance-enhancing agent is applied, the printing mechanism becomes complicated and unless the liquid absorption capacity of the ink receiving layer is fully increased, a bleeding phenomenon, in which the ink images are blotted, occurs.
Further, in the system using the water resistance-enhancing agent, a maintenance not only for the ink but also for the water resistance-enhancing agent is necessary and thus the printing cost increases.
When the ink jet recording material is used for the label on which the recorded images are absolutely necessary to exhibit a high storage stability, there is a strong demand of applying a pigment ink to the label. When the pigment ink is used, the pigment ink images applied to a surface of the recording material must be immediately fixed to the recording surface. In a conventional fixing mechanism, the pigment particles are anionically dispersed in a ink medium, and a cationic component is contained in the ink receiving layer, to agglomerate the anionically dispersed pigment particles with the cationic component. When the dye ink in which the dye is usually anionic is used, a large amount of the cationic component must be contained in the ink receiving layer. However, when the pigment ink is used, and the cationic component is contained in too large an amount in the ink receiving layer, the pigment particles are rapidly agglomerated at the surface of the ink receiving layer and thus the ink cannot be uniformly distributed in the images, and a feathering phenomenon occurs to reduce the color density of the ink images. Therefore, the conventional ink jet recording material suitable for the dye ink printing system cannot record thereon pigment ink images having a high quality.
An object of the present invention is to provide an ink jet recording material for recording thereon high dignity ink images containing a coloring pigment and having a high color density, by an ink jet recording system, for example, an ink jet recording printer or plotter, at a high printing speed, without blotting the ink images, and an ink jet recording method using the recording materials.
Another object of the present invention is to provide an ink jet recording material capable of recording thereon pigment-containing ink images, having a high clarity and an excellent weathering resistance, and useful for industrial use in which the printed ink images must exhibit a high color density, a high water resistance, and a high color fastness to rubbing, and the recording material must have a high pigment ink-fixing performance, and an ink jet recording method using the recording material.
The above-mentioned objects can be attained by the ink jet recording material and the ink jet recording method of the present invention.
The ink jet recording material of the present invention for recording thereon ink images containing a coloring material, comprises
a support; and
an ink receiving layer formed on the support, and comprising a pigment comprising at least one member selected from the group consisting of an amorphous silica, alumina and alumino silicate and a binder,
the ink receiving layer further comprising a cationic resin having a cation equivalent of 1.5 to 6 milli equivalent/g, determined by a colloid titration method.
In the ink jet recording material of the present invention, the cation equivalent of the cationic resin is preferably in the range of from 1.5 to 5 milli equivalent/g, more preferably from 2 to 4 milli equivalent/g.
In the ink jet recording material of the present invention, the cationic resin preferably comprises at least one selected from polyethylene imines, polyvinylpyridines, poly-dialkylaminoethyl methacrylates, poly-dialkylaminoethyl acrylates, poly-dialkylaminoethyl methacrylamides, poly-dialkylaminoethyl acrylamides, polyepoxyamines, polyamideamines, dicyandiamide-formaldehyde condensation products, dicyandiamidepolyalkyl-polyalkylenepolyamine condensation products, polymers of diallyldimethyl ammonium salts, polyvinylamines, polyallylamines polyallylamine salts, polyvinylamine salts, poly(oxyethyl-1-methylene)amine salts, polyvinylbenzylamine salts, polyacrylamido-propylmethylamine salts, polydiallylamine salts, acrylamide-diallylamine salt copolymers, monoallylamine-diallylamine salt copolymers and polyaminedicyan polymers, more preferably polydiallyldimethyl ammonium salts.
In the ink jet recording material of the present invention, the cationic resin preferably has a weight average molecular weight of 30,000 or less.
In the ink jet recording material of the present invention, the pigment for the ink receiving layer preferably comprises amorphous silica.
In the ink jet recording material of the present invention, the pigment for the ink receiving layer is preferably in the form of particles having an average particle size of 4 to 15 xcexcm.
In an embodiment of the ink jet recording material of the present invention, the cationic resin has a cation equivalent of 2 to 4 milli equivalent/g and is present together with an additional cationic resin having a cation equivalent of 4.5 to 8 milli equivalent/g and the pigment.
The pigment usable for the embodiment preferably has an oil absorption of 70 ml/100 g or more.
In the ink jet recording material of the present invention, the coloring material for the ink images is preferably a coloring pigment.
The method of the present invention for ink jet recording on the ink jet recording material of the present invention, as defined above comprises jetting imagewise ink droplets containing a coloring pigment toward a surface of the ink jet recording material.